Characterization of a cDNA clone encoding a Brassica napus 12 S protein (cruciferin) subunit. Relationship between precursors and mature chains.
Cruciferin (12 S globulin) is a large, neutral, oligometric protein synthesized in rapeseed (Brassica napus) during seed development. It is the major seed protein and is composed of six subunit pairs. Each of these pairs is synthesized as a precursor containing one heavy alpha-chain and one light beta-chain. Electrophoretic analysis of cruciferin showed that four different alpha- and four different beta-chains exist. A cruciferin clone was selected from an embryo cDNA library. This clone, pCRU1, contains a 1518-base pair open reading frame corresponding to a truncated NH2-terminal signal sequence followed by an alpha-chain of 296 and a beta-chain of 190 amino acid residues. Individual cruciferin chains as well as peptides thereof were subjected to NH2-terminal amino acid sequence analysis. The sequences obtained from a specific alpha- and beta-chain pair (alpha 1 and beta 1) showed total identity with the deduced amino acid sequence from pCRU1. Further comparisons revealed that a previously characterized cruciferin cDNA clone encodes one of the precursors for the closely related alpha 2/ alpha 3-beta 2/beta 3 subunits. The deduced amino acid sequences of the two cDNA clones display 64% similarity.
Rödin
J
J
Department of Cell Research, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, Sweden.
Ericson
M L
ML
Josefsson
L G
LG
Rask
L
L
D000485:Allergens; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D001937:Brassica / Q000235:genetics*; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics; D004247:DNA / Q000235:genetics*; D015723:Gene Library; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000302:isolation & purification; D011498:Protein Precursors / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D055314:Seed Storage Proteins
D000485:Allergens; D052179:Antigens, Plant; D003062:Codon; D046911:Macromolecular Substances; D010940:Plant Proteins; D011498:Protein Precursors; D055314:Seed Storage Proteins; C059777:cruciferin protein, Brassica napus; D004247:DNA